Linnaeus thanks Cadwallader Colden for his letter of 9 February 1748-9 [Cadwallader Colden to Linnaeus, 20 February 1749{L1015}], which he read with great satisfaction. Colden’s opinion on the generation of plants is the same as John Mitchell’s in Acta Naturae Curiosorum [Linnaeus refers to Mitchell’s treatise, ”D.D. Jo. Mitchell Dissertatio brevis de principiis botanicorum et zoologorum”]. Colden maintains that two species are of the same genus if they can produce offspring. Linnaeus does not call these distinct genera but varieties. For example, Ranunculus has several species, and nobody will deny that they belong to the same genus. However, they cannot possibly fertilize each other. On the other hand, Tulipiae and Brassicae, which are only varieties, can easily do so.
All the obscurities concerning botanical terminology Linnaeus has explained in Philosophia botanica, but it is being printed and has not yet been published. Linnaeus is sorry he cannot send a copy this time. In it Colden will find everything he needs.
Linnaeus sends the Acta Upsaliensia of 1743, where Colden can find the first part of his descriptions [Linnaeus here refers to his catalogued collection of plants brought together in the surroundings of his country seat, Coldengham, and communicated to Linnaeus, who published them under the title “Plantae Coldenhamiae"]. The second part will appear in the issue of 1744, but it has not yet left the printer. The second part was published in 1751].
If Colden has more material to present, Linnaeus will be happy to publish it. Linnaeus would appreciate it if Colden would be so kind as to send some dried plants and seeds. This can be taken care of by the Swedish clergymen [at the Swedish congregation in Raccoon]. If Colden would like something from Sweden, Linnaeus will be happy to forward it. Many of Colden’s plants are very rare and have not been seen or described before. Linnaeus would love to have them in his herbarium. He sends his regards and grateful wishes to his ”Maecenas in Flora’s service”.